In their recent paper on how to avoid dangerous climate change, Y. Xu and V. Ramanathan propose strategies to keep global warming within 1.5°C by 2100 (relative to 1900). One strategy was to seriously reduce emissions of methane, a potent short-lived greenhouse gas. The energy sector and cows account for almost half of anthropogenic methane emissions. Other sources related to human activity include landfills, rice production, waste treatment, and biomass burning.
First, the energy sector. We're mostly talking methane leaks during the production, storage and transport of coal, oil, and (especially) natural gas. Fixing the leakage problem is more than affordable - it's actually profitable, because leaks cost Big Energy potential revenue to be gained from converting methane to more benign products. The reason why companies haven't moved more quickly to take advantage of this business opportunity is the upfront expense of equipment upgrades that would shut down the leaks. Making money costs money. But governments, business and international organizations are working on it and slowly but surely equipment is being bought, practices changed, and leaks will not out. California, for instance, anticipates emissions from oil/gas sector "fugitive methane emissions" will be reduced at least 45% within 17 years. And we all know where California goes, the rest of the world will follow.
Next, cows. More specifically, burping (mostly) and farting cows. I'm not going to tell the poor struggling people of the developing world to just go vegan. Instead, I say: developed world, make cows the world over more productive, care of technologies already available. Check out this chart:
Don't think too hard about interpreting the chart - just go to the crux of the matter: you get a lot more cow protein with much less methane in North America and Europe than in the rest of the world. As it turns out, Latin America, South Asia, and parts of Sub Saharan Africa account for over two-thirds of cow-related methane emissions. The sinful meat eaters in the Northern Hemisphere are not driving these emissions. It's the low-productive cows of the less developed world, the ones that give little protein for all that gas. Help them! Improve feed quality, disease control, and grassland management. Select the best breeds for local conditions. Tweak their gut microbiota so that they're less gaseous. The developed world already knows how to do this - we just need to spread this wealth of knowledge and technology to the rest of the world and help them pay for coming up to speed.
Think about it: if, say, improved cows gave humans eight times the protein per unit of methane, global consumption of cow protein could double and livestock-related methane emissions would still go way down.
Ok, this is already a long post. Between gas, oil and cows, we've covered a lot of ground. I'm just going to end here with the assurance that much is being done to reduce methane emissions from rice production (flood less), landfills, waste treatment, and biomass burning. Visit the Global Methane Initiative website for much, much more